Various compositions heretofore utilized as food material for fish maintained in aquariums or under similar environmental conditions have long been recognized as lacking properties desirable for maintenance of the fish in healthy state for long periods of time. Such compositions have generally been composed of mixtures having a lower percentage of fat than recent studies show to be conductive to healthy growth of the fish. In particular it has been recognized by those skilled in the art that the aqueous environment in which fish live in aquariums is such an efficient heat-transfer medium that the utilization of protein by fish and their growth rate are limited by the relatively low available energy content of their food. In cases where fish have become sickly because of a diet too low in fat, they can at times be nourished back to healthy state by feeding them corn meal, a source of carbohydrate and protein, soaked in corn oil. This procedure indeed often results in dramatic growth rates of the fish.
Where corn meal soaked in corn oil is used to feed fish in aquariums, however, the water is required to be changed at frequent intervals (approximately every several hours) due to the fact that the film of fat which forms on the surface when the feed is placed in the water constitutes an oxygen barrier, thus inducing bacterial growth, which clouds the water and further depletes the oxygen content of the water that the fish need in order to live.
There are suggestions and proposals in the prior art of compositions comprising carbohydrate material and fatty or protein material and methods of making them, sometimes in the form of discrete particles. Among such suggestions and proposals are the following:
1. Suzuke, U.S. Pat. No. 1,083,769, Jan. 6, 1914, pertaining to a food for fish or animals which is made by boiling fish in water, pressing the liquid out of the boiled fish, extracting oil from the water and then mixing the water with starchy material to form a paste which is dried.
2. Hamburg, U.S. Pat. No. 1,124,611, Jan. 12, 1915, pertaining to compositions composed of fats or fatty oils in combination with highly concentrated malt extract.
3. Dunham, U.S. Pat. Nos. 1,431,938 and 1,432,057, both dated Oct. 17, 1922, and both relating to shortening agents composed of dry pulverulent mixtures of edible oils and starch material. In U.S. Pat. No. 1,431,938 the starch material is boiled in water to form what is substantially a solution, oil is emulsified with the solution in a proportion of two parts oil to one part starch, and the emulsion dried. In U.S. Pat. No. 1,432,057 the starch is mixed with cold water so as not to break the starch granules, oil is emulsified therewith in a proportion varying from 20% oil to 80% starch to 70% oil to 30% starch, and the emulsion dried at low temperature. The object is to produce a powder that will release its oil when it is mixed with flour, liquids and the ingredients used in making bread, biscuits, cakes and pastry.
4. Yudowitch, U.S. Pat. No. Re 16,919, Mar. 20, 1928, relating to an edible fat that has been obtained by boiling fat with onions, strained and cooled until hardened.
5. Eshbaugh, et al., U.S. Pat. No. 2,385,068, Sept. 18, 1945, which relates to a product containing about 20-25% protein, 5-15% fat, and 25-50% cereal. It comprises cooking and partially dehydrating starch and protein containing materials to a moisture content of about 33-45%, comminuting the partially dried and cooked material and then completing the drying of the comminuted product.
6. Kimball et al., U.S. Pat. No. 2,471,435, May 31, 1949, relating to dried powder ingredients useful in food mixes, particularly dry salad dressings, and consisting of particles of fat globules and egg fractions encysted with a gelatinized starchy substance and sugar.
7. Hintz et al., U.S. Pat. No. 2,554,143, May 23, 1951, pertaining to a dry pudding composition comprising pregelantinized pudding starch and an oleaginous material.
8. Bernhart et al., U.S. Pat. No. 2,611,706, Sept. 23, 1952. This relates to a food composition wherein milk solids are combined with a carbohydrate such as lactose, dextrine, insulin, or the like, and a fat component consisting of a blend of a plurality of fats of specified fatty acid content.
9. Schoch et al., U.S. Pat. No. 2,876,160, Mar. 3, 1959. This relates to compositions in dry, free-flowable form. It discloses water-insoluble liquids or solids imbedded or dispersed in a continuous starch matrix in order to protect the dispersed material from oxidation by air, chemical changes, and the like.
10. Ohtaki, U.S. Pat. No. 3,007,798, Nov. 7, 1961. This patent concerns preparation of corn powder by spray drying of an emulsion of ground corn and an edible fatty material. The fat particles present in the product are individually coated with a film of sweet corn protein and amylaceous substance of the sweet corn.
11. Colby, U.S. Pat. No. 3,257,213, June 21, 1966, pertaining to a method of preparing high shortening containing pastry mix which has a weight ratio of starch to shortening in the range of 1:1 to 4:1 and which is made by mixing the starch and shortening in the stated proportions with sufficient water to form a homogeneous slurry and spray drying this slurry to form the dry particles.
12. Marotta et al., U.S. Pat. No. 3,300,319, Jan. 24, 1967, pertaining to a solid sauce base comprising an edible lipid intimately admixed with a starch conversion product consisting of dextrines and oxydized starches having a water fluidity value of at least 65 as determined by the test described in the patent.
13. Kessinger, U.S. Pat. No. 3,396,035, Aug. 6, 1968. In this patent there are disclosed non-caking shortening compositions utilizing up to 80% by weight of shortening and not less than 20% gelatinized starch of specified particle size, bulk density, cold water solubility and moisture content. The gelatinized starch serves as a fat absorbent in dry bakery mixes.
14. Stein, U.S. Pat. No. 3,483,002, Dec. 9, 1969, pertaining to a gelatinous coloring composition comprising a food color, a sugar, an edible gum, a hydrogenated vegetable oil as a fusing agent which is solid at room temperature and a binder of gelatin or starch.
15. Wurzburg et. al., U.S. Pat. No. 3,499,962, Mar. 10, 1970. This patent discloses encapsulation of water-insoluble materials such as vegetables, oils, perfumes, vitamins, etc., in the dried product of an emulsion, the continuous phase of which is an aqueous solution of an amylose resulting from fractionation of starch, or of mixtures of low amylose starch with starch containing at least 40% amylose, to provide a protective shell for the encapsulated water-insoluble material. The patent mentions (col. 5, line 45) use of such encapsulated paticles in animal feeds.
16. Maloney et al., U.S. Pat. No. 3,505,076, Apr. 7, 1970. This relates to production of a food product by impregnating a puffed cereal matrix, composed of cereal grains or cereal doughs, with a starch-fat slurry, to coat the surface of the matrix.
17. Rock et al., U.S. Pat. No. 3,518,092, June 30, 1970, relating to a sugar-dusting composition comprising a powdered mixture of 53-92.5% sugar, 4-30% starch, 2-8% shortening and 0.5-9% of waxy material.
None of these proposals pertains to a water stable starch-lipid composition suitable for the uses to which the present invention can be put nor to the methods for preparing such compositions according to the method of the present invention.